SEARCH · PubMed Health

Results for “Sarcoma, Ewing”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed2006

Impact of FDG PET for staging of Ewing sarcomas and primitive neuroectodermal tumours.

AIM: High-grade Ewing sarcomas and Primitive neuroectodermal tumours (PNET) make up the tumours of the Ewing family. Our purpose was to evaluate the value of [18F]fluorodeoxyglucose positron emission tomography (FDG PET) in patients with Ewing tumours. PATIENTS AND METHODS: Twenty-four patients who had PET because of a suspected Ewing tumour during a 5-year period were included in this retrospective study. The images of 33 whole-body FDG PET investigations performed in primary or secondary diagnostics were analysed visually and semi-quantitatively by using standardized uptake values (SUVs). In 14 cases, PET was compared to bone scintigraphy regarding bone lesions. The final diagnosis was based on histology, imaging and follow-up. RESULTS: Histologically, the primary lesions were 10 Ewing sarcoma, 13 PNET and one osteomyelitis. The sensitivity and specificity of an examination-based analysis (presence of Ewing tumour and/or its metastases) were 96 and 78%, respectively. Altogether, 163 focal lesions were evaluated. Sensitivity and specificity regarding individual lesions were 73 and 78%. This lower sensitivity is mainly due to small lesions. In true-positive cases, the mean SUV was 4.54+/-2.79, and the SUVs in two false-positive cases were 4.66 and 1.60. True-positive and false-positive cases could not be differentiated definitively based on SUVs because of overlap and low values in true-positive lesions. In four cases, PET depicted 70 while bone scintigraphy depicted only eight bone metastases. CONCLUSION: An FDG PET investigation is a valuable method in the case of Ewing tumours. PET is superior to bone scintigraphy in the detection of bone metastases of Ewing tumours. For the depiction of small lesions, mainly represented by pulmonary metastases, PET is less sensitive than helical computed tomography. Determination of the role of whole-body FDG PET in diagnostic algorithm needs further investigation.

Adolescent↗

PubMed2006

Angiogenesis and Ewing sarcoma--relationship to pulmonary metastasis and survival.

BACKGROUND/PURPOSE: Intratumoral angiogenesis quantified by microvessel density (MVD) has been shown to be a strong prognostic indicator in a number of malignant tumors. Its association with prognosis in Ewing sarcoma has not been previously studied. The aim of our study was to investigate the relationship between angiogenesis and clinical outcome in Ewing sarcoma. METHODS: Twenty-seven patients with Ewing sarcoma were included in a retrospective immunohistochemical study. Sections from diagnostic biopsies were immunostained using anti-von Willebrand factor antibody and microvessels were counted at 400x magnification on three microscopic fields per patient. Microvessel density was correlated with overall and disease-free survival as a continuous variable using univariate regression analysis and as a dichotomous variable by Kaplan-Meier and log-rank analysis. Correlation between clinicopathologic variables and the degree of angiogenesis was tested using chi(2) test. RESULTS: Increasing MVD was not confirmed to be a poor prognostic factor in univariate analysis. Also, statistically significant difference was not found in overall survival or disease-free survival between patients with high (>31.6 vessels per field) and low (<or=31.6 vessels per field) microvessel counts. Finally, there was no difference regarding the metastatic rate between patients with high and low microvessel counts. CONCLUSIONS: Our results did not confirm increasing angiogenesis quantified by MVD to be predictive of prognosis or pulmonary metastasis in Ewing sarcoma. The diffuse pattern of distribution of microvessels found in Ewing sarcoma may be responsible for the observed lack of prognostic significance of angiogenesis. Future work is required to assess the prognostic importance of MVD in this disease.

Adolescent↗

PubMed2006

[Preliminary report of combination chemotherapy including Arsenic trioxide for stage III osteosarcoma and Ewing sarcoma].

OBJECTIVE: To determine the efficacy of Arsenic trioxide combined with other chemo agents in patients with metastatic osteosarcoma and Ewing sarcoma. METHODS: From December 2002 to June 2005, 32 patients with metastatic osteosarcoma and Ewing sarcoma were treated with chemotherapy comprised Arsenic trioxide, including 19 male and 13 female, aging from 7 to 32 years. Diagnoses included 27 cases with osteosarcomas and 5 with Ewing sarcomas. Twenty-five and 7 patients had multiple lung and skeletal metastasis respectively. All patients had received 4 to 6 cycles standard chemotherapy and surgical treatments before the metastatic lesions were found. The chemotherapy protocol consisted of Arsenic trioxide, VP-16 and paclitaxel. Twenty-eight patients accepted 2 cycles, and 4 patients accepted 3 cycles chemotherapy. RESULTS: Five patients (15.6%), whose lung focus disappeared and no new metastases proved, got complete response (CR); Six patients (18.8%) got partial response (PR); In thirteen stable disease (SD) patients (40.6%), the metastatic lesions did not reduce in evidence but completely calcified in 2 patients and partly calcified in 11 patients; Eight patients (25%) whose tumor size was even bigger after the chemotherapy were defined as progress disease (PD). The average follow-up period was 20 months (ranging from 6 months to 3 years). Three patients were eventually died; The disease was progressed in 5 patients, and the tumor growth was controlled in 24 patients. CONCLUSIONS: Arsenic trioxide is a low-toxic and effective remedy for treatment of stage III osteosarcoma and Ewing sarcoma.

Adolescent↗

PubMed2006

Primary Ewing sarcoma of the petrous temporal bone: an exceptional cause of facial palsy and deafness in a nursling.

BACKGROUND: Primary Ewing sarcoma affecting the skull base in general and the petrous bone in particular is extremely rare with only 4 reports of Ewing sarcoma arising in the petrous temporal bone in the international medical literature. METHODS: The authors report for the first time a case of a primary Ewing sarcoma of the petrous temporal bone in a 5-month-old nursling, which became apparent with a complete peripheral facial palsy and ipsilateral surdity. RESULTS: The neoformation was treated by systemic chemotherapy and radiation of the tumor region. The diagnostic steps, therapy, and development of the child are described in detail; the literature concerning Ewing sarcoma originating from the skull in general and from the petrous temporal bone in particular is reviewed. CONCLUSIONS: The highlights of this case are an extremely uncommon location, an unusual age of presentation, as well as a unique set of symptoms.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2003

2-Methoxyestradiol induces apoptosis in Ewing sarcoma cells through mitochondrial hydrogen peroxide production.

The Ewing sarcoma is the second most common bone tumor in children and young adults. Despite the advances in therapy, the 5-year survival rate for patients with metastatic disease is poor, indicating the need for alternative treatments. Here, we report that 2-methoxy-estradiol (2-Me), a natural estrogen metabolite, induced a caspase-dependent apoptosis of Ewing sarcoma-derived cells independently of their p53 status. 2-Me-induced apoptosis occurred through the mitochondrial death pathway as evidenced by reduction of the mitochondrial transmembrane potential, cytochrome c release and caspase-9 activation. Treatment of cells with 2-Me resulted in generation of intracellular H(2)O(2), which occurred earlier than caspase-9 activation. The H(2)O(2)-reducing agent Ebselen and the lipid peroxidation inhibitor vitamin E decreased both 2-Me-induced caspase-9 activation and cell death, thus providing evidence for a role of H(2)O(2) and lipid peroxides in the initiation of this process. Rotenone, an inhibitor of the mitochondrial respiratory chain, abolished both apoptosis and H(2)O(2) production, thereby identifying mitochondria as the source of H(2)O(2). Moreover, we observed that treatment of cells with 2-Me or H(2)O(2) induced activation of the c-Jun N-terminal kinase (JNK). Overexpression of a dominant-negative mutant of JNK1 reduced 2-Me-induced apoptosis indicating that JNK participates in this process. Altogether, our results provide evidence that 2-Me triggers apoptosis of Ewing sarcoma cells through induction of a mitochondria redox-dependent mechanism and suggest that this compound or other agents that selectively increase the level of reactive oxygen species may prove useful to the development of novel strategies for treatment of Ewing tumors.

2-Methoxyestradiol↗

PubMed1999

Nonmetastatic pelvic Ewing sarcoma: report of the French society of pediatric oncology.

BACKGROUND: Since January, 1984, 59 children with histologically confirmed Ewing sarcoma of the pelvic bone have been treated with three successive chemotherapy protocols recommended by the French Society of Pediatric Oncology. The purpose of the current study was to evaluate the role of surgery and/or radiotherapy in local progression-free, disease-free, and overall survivals (LPFS, DFS, and OS, respectively). PROCEDURE: We retrospectively examined 59 children treated for nonmetastatic, pelvic Ewing sarcoma over the last 12 years. All were first treated with chemotherapy according to the current French protocol. Six patients developed progressive disease before local treatment and were excluded for local control and survival analysis. Local treatment was surgery alone in 17 cases, radiation therapy in 27 cases, and surgery plus radiation therapy in 9 cases. RESULTS: With a median of follow-up of 6.5 years, no significant differences in local control or survival were observed with the three chemotherapeutic protocols. Of the 53 patients evaluable for local control, 6 relapsed locally only, 8 had local and distant relapses, and 9 had distant metastases only. The 5-year OS rate was worst for patients with radiotherapy alone compared to those with surgery or combined modality treatment (44 % vs. 72 %, P = 0.043). The 5-year LPFS and DFS rates were worst in the radiotherapy-alone group but not significantly (63% vs. 79%, P = 0. 22 and 42% vs 71%, P =0.07, respectively). The importance of surgery to OS and DFS was confirmed by multivariate analysis (P = 0.026 and P = 0.048, respectively). One surviving patient was diagnosed with in-field fibrosarcoma, which was presumably radiation induced. CONCLUSIONS: Despite intensive, multiagent chemotherapy, survival from pelvic Ewing sarcoma has not improved over the past decade; however, the survival rate does not seem to be worse than that from Ewing sarcoma at other locations, insofar as at least 50% of the patients were cured. Surgery or a combination of surgery and radiation therapy are the best local treatment; exclusive radiation therapy should be reserved for patients with inoperable lesions or partially or nonchemosensitive tumors or when surgery would be an amputation.

Adolescent↗

PubMed1997

Multimodal therapy for children and adolescents with Ewing sarcoma: results of the First National Chilean Trial (1986-1991).

Thirty-seven patients with Ewing sarcoma were treated in the First National Chilean Trial for Ewing's Sarcoma (1986-1991), which comprised the St. Jude Ewing's 78 Study. All patients received cyclophosphamide, doxorubicin, vincristine, and Dactinomycin for a total treatment period of about 10 months, and all prescribed therapy was administered. Local therapy consisted of irradiation (RT) to the primary tumor, complete surgical resection, or a combination of both surgery and RT. Twenty-nine of these patients had localized tumors, 24% had pelvic primary tumors, 21 were males, and 20 were greater than 10 years of age at diagnosis. Twenty-one patients had tumors that were greater than 8 cm in largest diameter. Fourteen of the 29 patients with localized disease remain disease free at 23 to 91 months from diagnosis. Fourteen patients have died of-tumor-related complications and 1 of a secondary malignancy. Relapse was local only in 4, metastatic in 9, and local plus metastatic in 1. Only 1 of the 8 patients with metastatic disease at presentation remains disease free. Toxicity consisted primarily of myelosuppression and mucositis. We conclude that this form of relative intense multimodal therapy for children/adolescents with localized Ewing sarcoma is curative in about half of affected children as in the original St. Jude study, and that it can be safely given in a developing country, provided that careful attention to supportive care and treatment planning is given. Although these results represent improvement in outcome for our patients, more effective therapy is needed for children with Ewing sarcoma, especially those with metastatic disease at presentation.

Adolescent↗

PubMed2004

Ewing sarcoma: radiation dose and target volume.

BACKGROUND: The outcome of children and adolescents with Ewing sarcoma is impacted by many prognostic factors and often measured by estimates of: event-free, relapse-free, disease-free, or overall survival. However, the preferred assessment following radiation therapy is local control. PROCEDURE: A review of large group experiences over the past several decades was undertaken to assess the optimal radiation dose and volume for patients with localized, osseous Ewing sarcoma. New approaches and techniques to improve local control were also investigated. RESULTS: With multidisciplinary therapy, 5-year overall local control rates range from 58 to 93%. Following definitive irradiation, they are 53-86%. Recommended radiation therapy doses are 55.8-60.0 Gy. In the postoperative setting, gross disease requires 55.8 Gy; microscopic disease requires 45 Gy. Altered fractionation schemes have not improved local control. The appropriate irradiated volume is an involved field to the pretreatment tumor volume plus 2.0-2.5 cm margin, followed by a boost to the post-induction chemotherapy tumor volume with margin. Good radiation quality control with central review improves local control. Use of an involved radiation field requires accuracy in defining tumor volume. Techniques to improve local control include risk-adapted multidisciplinary therapy, intraoperative boost radiation, and high radiation doses as delivered by 3-dimensional conformal radiation. Intensity modulated and proton beam radiotherapy may offer an advantage at special sites. CONCLUSIONS: Innovative uses of radiation in the multidisciplinary setting will continue to provide excellent local control, improved function, and quality of life for young patients with localized Ewing sarcoma of bone.

Child↗

PubMed2005

Inhibition of platelet-derived growth factor-induced cell growth signaling by a short interfering RNA for EWS-Fli1 via down-regulation of phospholipase D2 in Ewing sarcoma cells.

EWS-Fli1, a fusion gene resulting from a chromosomal translocation t(11;22, q24;q12) and found in Ewing sarcoma and primitive neuroectodermal tumors, encodes a transcriptional activator and promotes cellular transformation. However, the precise biological functions of its products remain unknown. To investigate the role of EWS-Fli1 in cell growth signaling, we transfected Ewing sarcoma TC-135 cells with short interfering RNAs for EWS-Fli1. EWS-Fli1 knockdown reduced cell growth and platelet-derived growth factor (PDGF)-BB-induced activation of the growth signaling enzymes. Interestingly, phospholipase D2 (but not the PDGF-BB receptor) showed marked down-regulation in the EWS-Fli1-knocked down TC-135 cells compared with the control cells. In Ewing sarcoma TC-135 cells, the PDGF-BB-induced phosphorylation of growth signaling involving extracellular signal-regulated kinase, Akt, p70S6K, and the expression of cyclin D3 were markedly inhibited by transfection with short interfering RNA phospholipase (PL)-D2. The PDGF-BB-induced activation of growth signaling was also suppressed by 1-butanol, which prevents the production of phosphatidic acid by phospholipase D (but not by t-butyl alcohol), thereby implicating PLD2 in PDGF-BB-mediated signaling in TC-135 cells. These results suggest that EWS-Fli1 may play a role in the regulation of tumor proliferation-signaling enzymes via PLD2 expression in Ewing sarcoma cells.

Becaplermin↗

PubMed2006

Local control in pelvic Ewing sarcoma: analysis from INT-0091--a report from the Children's Oncology Group.

PURPOSE: The impact of the modality used for local control of Ewing sarcoma is uncertain. We investigated the relationship between the type of local control modality, surgery, radiation (RT) or both (S + RT), and subsequent risk for local failure (LF) in patients with nonmetastatic pelvic Ewing sarcoma treated on INT-0091. PATIENTS AND METHODS: Patients < or = 30 years with Ewing sarcoma, primitive neuroectodermal tumor or primitive sarcoma of bone were randomly assigned to receive chemotherapy with doxorubicin, vincristine, cyclophosphamide, and dactinomycin, (VACA) or with these four drugs alternating with ifosfamide and etoposide (VACA-IE). The local control modality, surgery, RT or both was chosen by the treating physicians. The effect of local control modality was assessed after adjusting for the size of tumor (< 8 cm, > or = 8 cm) and chemotherapy type. RESULTS: Seventy-five patients with pelvic tumors and a median follow-up of 4.4 years (0.6 to 11.4 years) comprised the study population. Twelve underwent surgery, 44 received RT, and 19 received both. The 5-year event-free survival (EFS) and cumulative incidence of LF was 49% and 21% (16%, LF only; 5%, LF and distant failure). There was no significant difference in EFS or LF by tumor size (< 8 cm, > or = 8 cm), local control (LC) modality, or chemotherapy. However, VACA-IE seems to confer an LC benefit (11% v 30%; P = .06). CONCLUSION: There was no significant effect of local control modality (surgery, RT or S + RT) selected by the treating physicians on rates of local failure or EFS. However, VACA-IE improves LC (11%) compared with previously published results for pelvic Ewing sarcoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2004

VIP (etoposide, ifosfamide, cisplatin) in adult patients with recurrent or refractory Ewing sarcoma family of tumors.

Despite the fact that Ewing sarcoma family of tumors (ET) is chemosensitive, long-term survival is extremely rare for patients with primary refractory or recurrent disease. There is no standard salvage chemotherapy regimen available in this context. In this study the authors reviewed their experience with the combination of etoposide, ifosfamide, and cisplatin in adult patients with recurrent or refractory disease. From February 1997 through December 2001, they evaluated the efficacy of etoposide (75 mg/m2/day for 5 days), ifosfamide (1,200 mg/m2/day for 5 days), and cisplatin (20 mg/m2/day for 5 days) combination chemotherapy (VIP regimen), as second-line salvage therapy in 27 patients with recurrent or refractory ET. All patients were evaluated for response, time to progression, and overall survival. Twenty-one male and 6 female patients with recurrent (n = 14) and refractory (n = 13) disease were treated with the VIP regimen. Median age was 18 years (range, 16-34 years). Twenty-two patients were previously treated with vincristine, Adriamycin, ifosfamide, and actinomycin-D; and 5 patients were treated with cyclophosphamide, Adriamycin, and vincristine. Sites of recurrent or progressive disease included local (n = 3), distant (n = 11), and both local and distant (n = 13). A total of 129 cycles of VIP were given (median, 5 cycles/patient; range, 1-14 cycles/patient). One patient (4%) had a complete response (CR) and 8 patients (30%) had a partial response (PR), for an overall response rate of 34%. The median number of cycles given to patients with CR + PR was 6 (range, 3-14 cycles). Nine patients (33%) had stable disease and 9 (33%) had disease progression. Median time to progression and median overall survival were 6.6 months and 8.1 months respectively for all patients, and 12.8 months and 14.2 months respectively for responders. There were no toxic deaths. Major toxicities included grade IV granulocytopenia in 19 patients and grades III/IV thrombocytopenia in 15 patients. At a median follow-up of 8 months (range, 2-56 months), 24 patients died of disease progression, 2 patients are alive with disease, and 1 patient is alive with no evidence of disease. The authors conclude that the VIP combination is active in patients with recurrent/refractory ET, with acceptable toxicity, and offers good palliation. Cisplatin-based combination chemotherapy merits further investigation, possibly as first-line treatment in this disease.

Adolescent↗

PubMed1996

Outcome in 43 children presenting with metastatic Ewing sarcoma: the St. Jude Children's Research Hospital experience, 1962 to 1992.

The purpose of this work was to review the St. Jude Children's Research Hospital experience of patients presenting with metastatic Ewing sarcoma over a 30-year period. Forty-three of 212 cases of Ewing sarcoma presented with metastases at diagnosis. These patients were analyzed to determine whether primary tumor site or size, metastatic site(s), or advances in therapy have had a positive impact on survival. The overall survival for our 43 patients was 35% (95% confidence intervals, 20% to 50%). Comparing patients treated prior to 1979 with those treated after 1979, the overall survival was significantly different (P = 0.0002). Comparing overall survival between pelvic and non-pelvic primaries (P = 0.24), among metastatic sites (P = 0.83), and between tumors measuring > 8 cm in diameter to tumors measuring < 8 cm in diameter (P = 0.12), no significant differences were observed. Approximately one-third of patients presenting with metastatic Ewing sarcoma may achieve long-term survival. Children with metastatic Ewing sarcoma may benefit from clinical trials which intensify the doses of doxorubicin, and the highly effective combination of ifosfamide/etoposide.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1977

Extraskeletal Ewing sarcoma. An ultrastructural study.

Soft tissue tumors with the characteristics of Ewing sarcoma of bone have thus far only been studied by light microscopy. A pelvic tumor of this type in a 13-year-old girl was examined by electron microscopy. Comparison of its ultrastructural features with those of reported cases of bony Ewing sarcoma reveal much similarity. It is believed that they are probably identical and that the tumor cells are of immature mesenchymal type. However, their site of origin and the direction of their potential differentiation remain obscure.

Adolescent↗

PubMed2005

Oncogene-targeted antisense oligonucleotides for the treatment of Ewing sarcoma.

The genetic hallmark of the Ewing sarcoma family of tumours (ESFT) is the presence of the t(11;22)(q24;q12) translocation, present in up to 85% of cases of ESFT, which creates the EWS/FLI1 fusion gene and results in the expression of a chimeric protein regulating many other genes. The inhibition of this protein by antisense strategies has shown its predominant role in the transformed phenotype of Ewing cells. In addition, the junction point at the mRNA level offers a target for short therapeutic nucleic acids that is present only in the cancer cells and not in the normal tissues of a patient. Several teams have, therefore, investigated the activity of antisense oligonucleotides and siRNAs targeted against the junction point in mRNA; thus, inhibiting EWS/FLI1 synthesis. Generally speaking, the molecules induce a cell growth inhibition in culture. Apoptosis has also been reported. One laboratory has reported the in vivo tumour inhibitory effect of phosphorothioate antisense oligonucleotide directed against the EWS part of EWS/FlI1 when injected intratumourally. Independently, a tumour inhibitory effect of oligonucleotides targeting the junction point has been demonstrated provided they are delivered by polymeric nanoparticles through the intratumoural route. Alongside this target, other genes participating to the maintenance of the transformed phenotype of Ewing cells have been downregulated by antisense strategies.

Down-Regulation↗

PubMedDate not supplied

Fat-saturated contrast-enhanced T1-weighted MRI in evaluation of osteosarcoma and Ewing sarcoma.

To assess contrast-enhanced (C+), fat-saturated (FatSat), T1-weighted (T1W) imaging in the characterization of the soft tissue mass associated with primary bone tumors, we compared it with T2-weighted (T2W) imaging in patients with osteosarcoma (n = 36) and Ewing sarcoma family of tumors (Ewing sarcoma; n = 11). Periosseous tumor compared with normal muscle had greater contrast-to-noise ratio (CNR) on the FatSat T1W C+ image than on T2W for 81% (38/47; P < .0001) of patients. The CNR of periosseous tumor compared with subcutaneous fat was greater on FatSat T1W C+ for 98% (46/47; P < .0001). Radiologists found it easier to evaluate neurovascular bundle proximity to tumor with FatSat T1W C+ images than with T2W for 64% of patients (30/47; P < .0001). They judged FatSat T1W C+ superior to T2W for periosseous tumor conspicuity and visualization of soft tissue necrosis in 62% (29/47; P < .0001). In patients with osteosarcoma or Ewing sarcoma, FatSat T1W C+ imaging may replace T2W imaging for soft tissue mass evaluation, especially if contrast is being used for dynamic enhancement.

Adolescent↗

PubMed1999

Primary orbital Ewing sarcoma in a middle-aged woman.

A 43-year-old woman had unilateral exophthalmos caused by primary orbital Ewing sarcoma. Specialized immunohistochemical stains, primarily MIC-2 (CD99), aided in the diagnosis of Ewing sarcoma. Twenty-two months after radiotherapy and multiagent chemotherapy, the patient remained tumor free. To our knowledge, this is the first reported case of orbital Ewing sarcoma to present in an adult beyond the fourth decade of life.

12E7 Antigen↗

PubMed2005

Ewing sarcoma of the rib with normal blood flow and blood pool imagings on a 3-phase bone scan.

Ewing sarcoma is the second most common pediatric malignant bone tumor. It usually presents as a hot spot on a 3-phase bone scan as a result of increased vascularity of the tumor and new bone formation. However, aggressive Ewing sarcoma can also appear as a cold lesion. We present the features of a Ewing sarcoma of the rib on a 3-phase bone scan in a child who was being investigated for rib fracture after trauma.

Blood Flow Velocity↗

PubMed1982

Imaging of primary Ewing sarcoma with 13N-L-glutamate.

Eleven patients with untreated primary Ewing sarcoma were studied with intravenously administered 13N-labeled L-glutamate. Seven were repeatedly scanned during chemotherapy using this agent and 99mTc-methylene diphosphonate (99mTc-MDP). The untreated primary tumor was distinctly visualized with 13N-L-glutamate in all cases; the distribution of 13N label in the tumor sometimes differed from that of 99mTc. A kinetic study showed rapid uptake of 13N by tumor tissue. Repeat scans following therapy indicated that 13N-L-glutamate and 99mTc-MDP uptake showed changes consistent with histological findings following subsequent surgery. 13N uptake often decreased more markedly than 99mTc uptake during chemotherapy, but metastatic lesions were not visualized with 13N-L-glutamate. Tumor imaging with this labeled amino acid may be of value in assessing the response of primary Ewing sarcoma to chemotherapy.

Adolescent↗